1. Field of the Invention
The present invention relates to a semiconductor device configured by mounting a wiring board on a semiconductor chip, and a method for manufacturing the semiconductor device.
2. Description of the Related Art
Japanese Patent Laid-Open No. 9-260536 discloses a semiconductor device with a configuration in which a flexible wiring board is disposed on a principal surface of a semiconductor chip using an intervening elastomer placed between the flexible wiring board and the semiconductor chip, and an electrode pad of the semiconductor chip, and a lead part of wiring disposed in an aperture part of the wiring board are electrically connected. An external terminal is provided in the other surface of the wiring board. Sealing material made of insulating resin covers an electrode pad of the semiconductor chip, which is disposed in the aperture part of the wiring board, and covers the lead part.
Such a semiconductor device is configured so that the electrode pad of the semiconductor chip and the lead part of the wiring board are electrically connected in the aperture part which is provided in the wiring board. Thus, the semiconductor device is configured so that the external terminal can not be disposed around just below the electrode pad of the semiconductor chip.
Year by year, an operation rate of the semiconductor device has been increased. In the semiconductor device, since the distance from the electrode pad of the semiconductor chip, for example, a wiring distance becomes longer, the operation speed may be lowered. Thus, for the semiconductor devices, there is a requirement shorten substantially the wiring distance to prevent the operation speed from being lowered, and to obtain favorable electrical characteristics.
As described above, since it is difficult to dispose the external terminal around just below the electrode pad of the semiconductor chip, the number of the external terminals may be also decreased which are disposed in an area of the wiring board on which a semiconductor chip is mounted. In the semiconductor device, there is such a trend that the number of the external terminals is increased, and it becomes necessary to dispose the external terminals outside of the area of the wiring board on which the semiconductor chip is mounted, so that an area of the wiring board may become larger. If the area of the wiring board becomes larger, a package size of the semiconductor device may become larger. This is a problem. In addition, if the area of the wiring board becomes larger, the number of the wiring boards that can be manufactured in one process is decreased during the wiring board manufacturing process, and the manufacturing cost of the wiring board may be increased. This is also a problem.
The above semiconductor device related to the present invention is configured so that the semiconductor chip is mounted on the wiring board using an intervening elastomer (elastic material) placed between the flexible wiring board and the semiconductor chip to improve the reliability when the semiconductor device is mounted on a printed wiring board such as a motherboard, so-called, in the case of the secondary mounting. By mounting the semiconductor chip on the wiring board using an intervening elastomer placed between the flexible wiring board and the semiconductor chip, it is possible to reduce stress because of a difference between the thermal expansion coefficients, and to improve the reliability in the case of the secondary mounting. However, since elastomer is relatively expensive material, the manufacturing cost of the semiconductor device may be increased.
In the semiconductor device related to the present invention, the semiconductor chip is mounted on the flexible wiring board by using the TAB (Tape Automated Bonding) method. Thus, in this semiconductor device, because of the influence caused by the size tolerance or the roll of sheet material configured in the wiring board, there exists such a problem in which the required mounting accuracy can not be obtained or a problem in which expensive mounting equipment may become necessary. Since the pitch of the electrode pad, the wiring and the like of the semiconductor device trends to be narrower, it becomes also necessary to improve mounting accuracy.